Fri Apr 12 19:25:25 UTC 2024 Kernel update

Documentation/ABI/testing/sysfs-devices-system-cpu

@@ -517,7 +517,6 @@ What:		/sys/devices/system/cpu/vulnerabilities
 		/sys/devices/system/cpu/vulnerabilities/mds
 		/sys/devices/system/cpu/vulnerabilities/meltdown
 		/sys/devices/system/cpu/vulnerabilities/mmio_stale_data
-		/sys/devices/system/cpu/vulnerabilities/reg_file_data_sampling
 		/sys/devices/system/cpu/vulnerabilities/retbleed
 		/sys/devices/system/cpu/vulnerabilities/spec_store_bypass
 		/sys/devices/system/cpu/vulnerabilities/spectre_v1

Documentation/admin-guide/hw-vuln/index.rst

@@ -21,4 +21,3 @@ are configurable at compile, boot or run time.
    cross-thread-rsb.rst
    gather_data_sampling.rst
    srso
-   reg-file-data-sampling

Documentation/admin-guide/hw-vuln/spectre.rst

@@ -138,10 +138,11 @@ associated with the source address of the indirect branch. Specifically,
 the BHB might be shared across privilege levels even in the presence of
 Enhanced IBRS.
 
-Previously the only known real-world BHB attack vector was via unprivileged
-eBPF. Further research has found attacks that don't require unprivileged eBPF.
-For a full mitigation against BHB attacks it is recommended to set BHI_DIS_S or
-use the BHB clearing sequence.
+Currently the only known real-world BHB attack vector is via
+unprivileged eBPF. Therefore, it's highly recommended to not enable
+unprivileged eBPF, especially when eIBRS is used (without retpolines).
+For a full mitigation against BHB attacks, it's recommended to use
+retpolines (or eIBRS combined with retpolines).
 
 Attack scenarios
 ----------------
@@ -429,23 +430,6 @@ The possible values in this file are:
   'PBRSB-eIBRS: Not affected'  CPU is not affected by PBRSB
   ===========================  =======================================================
 
-  - Branch History Injection (BHI) protection status:
-
-.. list-table::
-
- * - BHI: Not affected
-   - System is not affected
- * - BHI: Retpoline
-   - System is protected by retpoline
- * - BHI: BHI_DIS_S
-   - System is protected by BHI_DIS_S
- * - BHI: SW loop; KVM SW loop
-   - System is protected by software clearing sequence
- * - BHI: Syscall hardening
-   - Syscalls are hardened against BHI
- * - BHI: Syscall hardening; KVM: SW loop
-   - System is protected from userspace attacks by syscall hardening; KVM is protected by software clearing sequence
-
 Full mitigation might require a microcode update from the CPU
 vendor. When the necessary microcode is not available, the kernel will
 report vulnerability.
@@ -500,18 +484,11 @@ Spectre variant 2
 
    Systems which support enhanced IBRS (eIBRS) enable IBRS protection once at
    boot, by setting the IBRS bit, and they're automatically protected against
-   some Spectre v2 variant attacks. The BHB can still influence the choice of
-   indirect branch predictor entry, and although branch predictor entries are
-   isolated between modes when eIBRS is enabled, the BHB itself is not isolated
-   between modes. Systems which support BHI_DIS_S will set it to protect against
-   BHI attacks.
+   Spectre v2 variant attacks, including cross-thread branch target injections
+   on SMT systems (STIBP). In other words, eIBRS enables STIBP too.
 
-   On Intel's enhanced IBRS systems, this includes cross-thread branch target
-   injections on SMT systems (STIBP). In other words, Intel eIBRS enables
-   STIBP, too.
-
-   AMD Automatic IBRS does not protect userspace, and Legacy IBRS systems clear
-   the IBRS bit on exit to userspace, therefore both explicitly enable STIBP.
+   Legacy IBRS systems clear the IBRS bit on exit to userspace and
+   therefore explicitly enable STIBP for that
 
    The retpoline mitigation is turned on by default on vulnerable
    CPUs. It can be forced on or off by the administrator
@@ -645,10 +622,9 @@ kernel command line.
                 retpoline,generic       Retpolines
                 retpoline,lfence        LFENCE; indirect branch
                 retpoline,amd           alias for retpoline,lfence
-                eibrs                   Enhanced/Auto IBRS
-                eibrs,retpoline         Enhanced/Auto IBRS + Retpolines
-                eibrs,lfence            Enhanced/Auto IBRS + LFENCE
-                ibrs                    use IBRS to protect kernel
+                eibrs                   enhanced IBRS
+                eibrs,retpoline         enhanced IBRS + Retpolines
+                eibrs,lfence            enhanced IBRS + LFENCE
 
 		Not specifying this option is equivalent to
 		spectre_v2=auto.
@@ -708,24 +684,6 @@ For user space mitigation:
 		spectre_v2=off. Spectre variant 1 mitigations
 		cannot be disabled.
 
-	spectre_bhi=
-
-		[X86] Control mitigation of Branch History Injection
-		(BHI) vulnerability. Syscalls are hardened against BHI
-		regardless of this setting. This setting affects the deployment
-		of the HW BHI control and the SW BHB clearing sequence.
-
-		on
-			unconditionally enable.
-		off
-			unconditionally disable.
-		auto
-			enable if hardware mitigation
-			control(BHI_DIS_S) is available, otherwise
-			enable alternate mitigation in KVM.
-
-For spectre_v2_user see Documentation/admin-guide/kernel-parameters.txt
-
 Mitigation selection guide
 --------------------------
 

Documentation/admin-guide/index.rst

@@ -82,7 +82,6 @@ configure specific aspects of kernel behavior to your liking.
    edid
    efi-stub
    ext4
-   filesystem-monitoring
    nfs/index
    gpio/index
    highuid

Documentation/admin-guide/kernel-parameters.txt

@@ -1037,26 +1037,6 @@
 			The filter can be disabled or changed to another
 			driver later using sysfs.
 
-	reg_file_data_sampling=
-			[X86] Controls mitigation for Register File Data
-			Sampling (RFDS) vulnerability. RFDS is a CPU
-			vulnerability which may allow userspace to infer
-			kernel data values previously stored in floating point
-			registers, vector registers, or integer registers.
-			RFDS only affects Intel Atom processors.
-
-			on:	Turns ON the mitigation.
-			off:	Turns OFF the mitigation.
-
-			This parameter overrides the compile time default set
-			by CONFIG_MITIGATION_RFDS. Mitigation cannot be
-			disabled when other VERW based mitigations (like MDS)
-			are enabled. In order to disable RFDS mitigation all
-			VERW based mitigations need to be disabled.
-
-			For details see:
-			Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
-
 	driver_async_probe=  [KNL]
 			List of driver names to be probed asynchronously.
 			Format: <driver_name1>,<driver_name2>...
@@ -3090,7 +3070,6 @@
 					       nopti [X86,PPC]
 					       nospectre_v1 [X86,PPC]
 					       nospectre_v2 [X86,PPC,S390,ARM64]
-					       reg_file_data_sampling=off [X86]
 					       retbleed=off [X86]
 					       spec_store_bypass_disable=off [X86,PPC]
 					       spectre_v2_user=off [X86]
@@ -5404,18 +5383,6 @@
 	sonypi.*=	[HW] Sony Programmable I/O Control Device driver
 			See Documentation/admin-guide/laptops/sonypi.rst
 
-	spectre_bhi=	[X86] Control mitigation of Branch History Injection
-			(BHI) vulnerability. Syscalls are hardened against BHI
-			reglardless of this setting. This setting affects the
-			deployment of the HW BHI control and the SW BHB
-			clearing sequence.
-
-			on   - unconditionally enable.
-			off  - unconditionally disable.
-			auto - (default) enable hardware mitigation
-			       (BHI_DIS_S) if available, otherwise enable
-			       alternate mitigation in KVM.
-
 	spectre_v2=	[X86] Control mitigation of Spectre variant 2
 			(indirect branch speculation) vulnerability.
 			The default operation protects the kernel from
@@ -5446,9 +5413,9 @@
 			retpoline,generic - Retpolines
 			retpoline,lfence  - LFENCE; indirect branch
 			retpoline,amd     - alias for retpoline,lfence
-			eibrs		  - Enhanced/Auto IBRS
-			eibrs,retpoline   - Enhanced/Auto IBRS + Retpolines
-			eibrs,lfence      - Enhanced/Auto IBRS + LFENCE
+			eibrs		  - enhanced IBRS
+			eibrs,retpoline   - enhanced IBRS + Retpolines
+			eibrs,lfence      - enhanced IBRS + LFENCE
 			ibrs		  - use IBRS to protect kernel
 
 			Not specifying this option is equivalent to

Documentation/core-api/dma-api.rst

@@ -204,20 +204,6 @@ Returns the maximum size of a mapping for the device. The size parameter
 of the mapping functions like dma_map_single(), dma_map_page() and
 others should not be larger than the returned value.
 
-::
-
-	size_t
-	dma_opt_mapping_size(struct device *dev);
-
-Returns the maximum optimal size of a mapping for the device.
-
-Mapping larger buffers may take much longer in certain scenarios. In
-addition, for high-rate short-lived streaming mappings, the upfront time
-spent on the mapping may account for an appreciable part of the total
-request lifetime. As such, if splitting larger requests incurs no
-significant performance penalty, then device drivers are advised to
-limit total DMA streaming mappings length to the returned value.
-
 ::
 
 	bool